Solid-state imaging systems or imaging readers have been used, in both handheld and/or hands-free modes of operation, to electro-optically read targets, such as one- and/or two-dimensional bar code symbols, each bearing elements, e.g., bars and spaces, of different widths and reflectivities, to be decoded, as well as forms, such as documents, labels, receipts, signatures, drivers' licenses, identification badges, and payment/loyalty cards, each bearing one or more form fields, typically containing alphanumeric characters, or images, or bar code symbols.
A known exemplary imaging reader includes a housing either held by a user and/or supported on a support surface, a window supported by the housing and aimed at the target, and an imaging engine or module supported by the housing and having a solid-state imager (or image sensor) with a sensor array of photocells or light sensors (also known as pixels), and an imaging lens assembly for capturing return light scattered and/or reflected from the target being imaged along an imaging axis through the window over a field of view, and for projecting the return light onto the sensor array to initiate capture of an image of the target over a range of working distances in which the target can be read. Such an imager may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device and associated circuits for producing and processing electrical signals corresponding to a one- or two-dimensional array of pixel data over the field of view. These electrical signals are decoded and/or processed by a programmed microprocessor or controller into information related to the target being read, e.g., decoded data indicative of a symbol, or characters or marks indicative of text in a form field of a form, or into a picture indicative of a picture on the form. A trigger is typically manually activated by the user to initiate reading in a handheld mode of operation. Sometimes, an object sensing assembly is employed to automatically initiate reading whenever a target enters the field of view in a hands-free mode of operation.
In the hands-free mode, the user may slide or swipe the target past the window in either horizontal and/or vertical and/or diagonal directions in a “swipe” mode. Alternatively, the user may present the target to an approximate central region of the window in a “presentation” mode. The choice depends on the type of target, operator preference, or on the layout of a workstation in which the reader is used. In the handheld mode, the user holds the reader in his or her hand at a certain distance from the target to be imaged and initially aims the reader at the target. The user may first lift the reader from a countertop or a support stand or cradle. Once reading is completed, the user may return the reader to the countertop or to the support stand to resume hands-free operation.
Although the known imaging readers are generally satisfactory for their intended purpose, one concern relates to reading different types of targets during a reading session. In a typical reading session, a majority of the targets are symbols, and a minority of the targets are forms that contain form fields, each containing text, or a picture, or a symbol, arranged at various locations on each form. There may be different types of forms of different, or the same, size. The known imaging readers require that the user must configure the reader to read each form prior to trigger activation. This configuring is typically done by having the user scan one or more configuration bar code symbols with the imaging reader during a calibration mode of operation, or by interacting the imaging reader with a host computer interface in which a host computer instructs the imaging reader to change its configuration, such that the microprocessor is taught to recognize a certain form. However, this advance configuring is a cumbersome process and requires the user to remember to select, and to switch to, the correct form prior to trigger activation.
Another concern relates to reading forms in a correct orientation. Forms are generally not omnidirectional. In a handheld reader, the user is required to rotate the form to a particular orientation. For example, a driver's license may have the same physical size as an employee badge, but the form fields of the driver's license are best read in a landscape orientation, while the form fields of the employee badge are best read in a portrait orientation.
In the prior art of hands-free readers, such as flatbed scanners, photocopiers, fax machines, and like fixed equipment, orientation detection is typically performed by optical character recognition (OCR). The forms are presented on a flat surface of the equipment, and at least one edge of the form is aligned with the equipment, in one of four directions. Typically, an OCR engine is given the same form, or parts of the form, in four separate directions. The direction (orientation) that correctly decodes the most number of characters, or decodes them with the highest confidence, is assumed to be correct. The orientations thus gotten from several different form fields may be combined to make a final decision for the correct orientation of the form. However, the OCR approach is generally slow. Performing OCR on a form imaged with an arbitrary rotation typically requires that the image may need to be rectified first, thereby causing further delays.
Orientation detection can also be performed by employing orientation marks. However, some forms may or may not come with these marks, and customization for this task alone may not be desirable. For example, if a merchant wants to scan the front of drivers' licenses for verification of the information (e.g., in comparison with the encoded information on the back of the drivers' licenses to prevent fraud), or to capture the picture on the licenses (which are not available as encoded information on the back), the merchant may not be able to affix orientation marks on the licenses. Margin detection can also be employed, but it only works if a form is known to contain significantly asymmetrical margins, such as printed material prepared for binding. However, not all forms have significantly asymmetrical margins.
Accordingly, there is a need to provide an arrangement for, and a method of, electro-optically reading forms by image capture, by automatically identifying each form in a streamlined fashion, and by automatically identifying a correct orientation of each form whose image is being captured, without performing advance OCR or requiring orientation marks.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The arrangement and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.